Conventional piles are metal tubes having either a circular or a rectangular cross-section. Such piles are mounted in the ground to provide a support structure for the construction of superstructures. The piles are provided in sections, such as seven-foot sections, that are driven into the ground.
Some piles have a cutting tip that permits them to be rapidly deployed. By rotating the pile, the blade pulls the pile into the ground, thus greatly reducing the amount of downward force necessary to bury the pile. For example, a pile may include a tip that is configured to move downward into the soil at a rate of three inches for every full revolution of the pile (three inch pitch). Since pre-drilling operations are unnecessary, the entire pile may be installed in under ten minutes. Unfortunately, the rotary action of the pile also loosens the soil which holds the pile in place. This reduces the amount of vertical support the pile provides. Traditionally, grout is injected around the pile in an attempt to solidify the volume around the pile and thus compensate for the loose soil. The current method of grout deployment is less than ideal. The addition of grout to the area around the pile typically is uncontrolled and attempts to deploy grout uniformly about the pile have been unsuccessful. Often the introduction of the grout itself can cause other soil packing problems, as the soil must necessarily be compressed by the introduction of the grout. A new method for introducing grout around a pile would be advantageous.
Helical or torqued in piles are used in various aspects of construction in order to establish compression or tension resistance in a supporting medium (e.g. soil, rock, etc.). Helical piles, for example, have a helical flighting on a first pile section defined by a pile shaft that is contacted to a surface of the supporting medium. Upon rotation, the helical flighting pulls the first pile section into the supporting medium. After the first pile section has reached a certain depth, a second pile section having a welded or forged coupling, is attached to the first pile section using at least one bolt through formed holes. Rotation of the second pile section applies a torque to the first pile section to continue the rotation and drive the helical pile to a greater depth in the supporting medium. Subsequent pile sections may be sequentially attached to enable the pile to reach a predetermined depth.
Conventional pile couplings are forged or welded to one end of the pile shaft and often are inserted into the second pile section within or around the first pile section and then fastened to the previous pile section together by inserting one or more pins through side holes formed in the pile coupling and the first pile section. Unfortunately, the applied torque that is produced during helical pile installation is significant and will cause elongation in the side holes. Further, the torque transfer depends on the weld at the coupling and weld failure is a recurrent problem. Some known pile couplings incorporate an additional forged end which is provided in order to help transfer the torsion load, but this latter feature is expensive to incorporate and involves additional welding. As a result, an improved pile coupling is therefore desired.
A pile coupling that would transfer a large portion of the torsional load directly down the pile shaft would advantageous, thereby resisting the torque that is to be resisted by the pins alone.